Technical Field
The present disclosure relates to a nanocomposite film comprising a polymer matrix and conductive carbon nanotubes dispersed in the matrix having a first surface with a first resistivity and a second surface with a second resistivity, a process for producing the nanocomposite film and an electronic device comprising the nanocomposite film. The present disclosure also relates to a nanocomposite film comprising a polymer layer, a polysaccharide layer and a conductive nanofiller layer sandwiched between the polymer layer and the polysaccharide layer, a process for producing the nanocomposite film and an electronic device comprising the electronic film.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
The shortage in petroleum resources and the rapid increase in the usage of non-biodegradable polymers pose a great risk to the environment. Development of polymer composites from biodegradable and renewable materials has attracted wide attention in scientific and technological communities owing to their interesting properties. Polymer composites filled by nanostructures have attracted significant attention as a result of their unique mechanical, electric and optical properties. Nano-scale conductive fillers can create a seamlessly interconnected percolative network within the polymer matrix altering the energy storing and transporting properties of the composite while reinforcing the native polymer and enhancing its mechanical strength.
Polyvinyl alcohol (PVA) is a synthetic, water soluble and biodegradable polymer that has been used in numerous applications including water soluble packaging films, drug delivery, paper coating, textile sizing, etc. PVA is well known for its biocompatibility and non-toxicity. PVA can easily be blended with a wide range of natural polymers and fillers to make biodegradable composites with outstanding properties. PVA has excellent properties such as biocompatibility, barrier properties to gases and liquids, hydrophilicity and chemical resistance [M. I. Baker, S. P. Walsh, Z. Schwartz, and B. D. Boyan, “A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications.,” J. Biomed. Mater. Res. B. Appl. Biomaler., vol. 100, no. 5, pp. 1451-7, July 2012.—incorporated herein by reference in its entirety].
Carbon nanotubes (CNTs) have attracted a great interest since they were discovered in 1991 [S. Iijima, “Helical microtubules of graphitic carbon,” Nature, vol. 354, no. 6348, pp. 56-58, November 1991.—incorporated herein by reference in its entirety]. They have a cylindrical structure of carbon atoms with excellent mechanical, electrical, thermal, optical and chemical properties. The Young's modulus and the tensile strength of carbon nanotubes are approximately 5 times and 50 times higher than those of steel, respectively. The thermal conductivity of carbon nanotubes is in the range of 1800-200 W/m-K [F. D. S. Marquis and L. P. F. Chibante, “Improving the heat transfer of nanofluids and nanolubricants with carbon nanotubes,” JOM, vol. 57, no. 12, pp. 32-43, December 2005.—incorporated herein by reference in its entirety]. In recent years, many studies have been carried out on the preparation and characterization of biopolymer nanocomposites based on CNTs [M. C. Paiva, B. Zhou, K. A. S. Fernando, Y. Lin, J. M. Kennedy, and Y.-P. Sun, “Mechanical and morphological characterization of polymer-carbon nanocomposites from functionalized carbon nanotubes,” Carbon N. Y., vol. 42, no. 14, pp. 2849-2854, January 2004.; and S.-I. Moon, F. Jin, C. Lee, S. Tsutsumi, and S.-H. Hyon, “Novel Carbon Nanotube/Poly(L-lactic acid) Nanocomposites; Their Modulus, Thermal Stability, and Electrical Conductivity,” Macromol. Symp., vol. 224, no. 1, pp. 287-296, April 2005.; and W. Chen and X. Tao, “Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes,” Appl. Surf. Sci., vol. 252, no. 10, pp. 3547-3552, March 2006.; and J. T. Yoon, Y. G. Jeong, S. C. Lee, and B. G. Min, “Influences of poly(lactic acid)-grafted carbon nanotube on thermal, mechanical, and electrical properties of poly(lactic acid),” Polym. Adv. Technol., vol. 20, no. 7, pp. 631-638, July 2009.; and W.-M. Chiu, Y.-A. Chang, H.-Y. Kuo, M.-H. Lin, and H.-C. Wen, “A study of carbon nanotubes/biodegradable plastic polylactic acid composites,” J. Appl. Polym. Sci., vol. 108, no. 5, pp. 3024-3030, June 2008.; and S. W. Ko, M. K. Hong, B. J. Park, R. K. Gupta, H. J. Choi, and S. N. Bhattacharya, “Morphological and rheological characterization of multi-walled carbon nanotube/PLA/PBAT blend nanocomposites,” Polym. Bull., vol. 63, no. 1, pp. 125-134, April 2009.; and S. Chen, G. Wu, Y. Liu, and D. Long, “Preparation of Poly(acrylic acid) Grafted Multiwalled Carbon Nanotubes by a Two-Step Irradiation Technique,” Macromolecules, vol. 39, no. 1, pp. 330-334, January 2006.; and Y.-L. Liu, W.-H. Chen, and Y.-H. Chang, “Preparation and properties of chitosan/carbon nanotube nanocomposites using poly(styrene sulfonic acid)-modified CNTs,” Carbohydr. Polym., vol. 76, no. 2, pp. 232-238, March 2009.; and F. Mai, Y. Habibi, J.-M. Raquez, P. Dubois, J.-F. Feller, T. Peijs, and E. Bilotti, “Poly(lactic acid)/carbon nanotube nanocomposites with integrated degradation sensing,” Polymer (Guildf)., vol. 54, no. 25, pp. 6818-6823, November 2013.; and J. Jose, S. K. De, M. A. AlMa'adeed, J. B. Dakua, P. A. Sreekumar, R. Sougrat, and M. A. Al-Harthi, “Compatibilizing role of carbon nanotubes in poly(vinyl alcohol)/starch blend,” Starch/Starke, vol. 66, pp. 1-7, October 2014.—each incorporated herein by reference in its entirety].
Starch is a natural biodegradable polymer and has several benefits such as availability, its low cost compared to synthetic polymers, and its full compostability without leaving any toxic residue [F. Xie, E. Pollet, P. J. Halley, and L. Avérous, “Starch-based nano-biocomposites,” Prog. Polym. Sci., vol. 38, no. 10-11, pp. 1590-1628, October 2013.—incorporated herein by reference in its entirety]. Starch can be used to enhance the properties as well as to decrease the cost of products incorporating it [M. Maiti, B. S. Kaith, R. Jindal, and A. K. Jana, “Synthesis and characterization of corn starch based green composites reinforced with Saccharum spontaneum L graft copolymers prepared under micro-wave and their effect on thermal, physio-chemical and mechanical properties,” Polym. Degrad. Stab., vol. 95, no. 9, pp. 1694-1703, September 2010.—incorporated herein by reference in its entirety]. However, the films formed from native starch have certain shortcomings such as brittleness and high water absorption [B. Chatterjee, N. Kulshrestha, and P. N. Gupta, “Electrical properties of starch-PVA biodegradable polymer blend,” Phys. Scr., vol. 90, no. 2, p. 025805, February 2015.—incorporated herein by reference in its entirety]. Blends of polyvinyl alcohol with starch have been widely studied in the literature [P. Sreekumar, M. a. Al-Harthi, and S. De, “Reinforcement of starch/polyvinyl alcohol blend using nano-titanium dioxide,” J. Compos. Mater., vol. 46, no. 25, pp. 3181-3187, February 2012.; and P. A. Sreekumar, M. A. Al-Harthi, and S. K. De, “Effect of glycerol on thermal and mechanical properties of polyvinyl alcohol/starch blends,” J. Appl. Polym. Sci., vol. 123, no. 1, pp. 135-142, 2012.; and P. A. Sreekumar, M. A. Al-Harthi, and S. K. De, “Studies on compatibility of biodegradable starch/polyvinyl alcohol blends,” Polym. Eng. Sci., vol. 52, no. 10, pp. 2167-2172, October 2012.; and S. P. Appu, S. K. De, M. J. Khan, and M. A. Al-Harthi, “Natural weather ageing of starch/polyvinyl alcohol blend: effect of glycerol content,” J. Polym. Eng., vol. 33, no. 3, pp. 1-7, January 2013.—each incorporated herein by reference in its entirety].
Graphene has a two-dimensional structure of carbon atoms in a hexagonal lattice with sheets having a thickness of just one atom (0.33 nm). The graphene has a layered crystal structure, in which the carbon atoms are strongly bonded on a two-dimensional network consisting of hexagons. Graphene combines the layered structure of clays with the excellent mechanical, thermal and electrical properties of carbon nanotubes to provide unique functional properties in final products. Since the isolation of a single sheet of graphene [K. S. Novoselov, A. K. Geim, S. V Morozov, D. Jiang, Y. Zhang, S. V Dubonos, I. V Grigorieva, a a Firsov, Science, vol. 306, no. 5696 (2004) 666-669.—incorporated herein by reference in its entirety], graphene has attracted the attention of researchers pursuing novel nanocomposites. Recently, it has received a substantial interest compared to the conventional nanofillers such as nanoclays and carbon nanotubes because of its exceptional electrical and mechanical properties, high aspect ratio, and low density [O. C. Compton and S. T. Nguyen, “Graphene oxide, highly reduced graphene oxide, and graphene: versatile building blocks for carbon-based materials,” Small, vol. 6, no. 6, pp. 711-23, March 2010.; and S. Sheshmani, A. Ashori, and M. A. Fashapoyeh, “Wood plastic composite using graphene nanoplatelets.,” Int. J. Biol. Macromol., vol. 58, pp. 1-6, July 2013.; and S. Sheshmani and R. Amini, “Preparation and characterization of some graphene based nanocomposite materials.,” Carbohydr. Polym., vol. 95, no. 1, pp. 348-59, June 2013.—each incorporated herein by reference in its entirety].
Graphene is known to be combined as a few layers (graphite) and different types of graphite nanoplatelets such as thermally expanded graphite, graphene oxide (GO) and chemically modified graphene have been used to make functional polymer nanocomposites [H. Kim, A. Abdala, C. W. Macosko, Macromolecules 43 (2010) 6515.; and C. Gomez-Navarro, J. C. Meyer, R. S. Sundaram, A. Chuvilin, S. Kurasch, M. Burghard, K. Kern, U. Kaiser, Nano Lett. 10 (2010) 1144.; and J. T. Robinson, F. K. Perkins, E. S. Snow, Z. Wei, P. E. Sheehan, Nano Lett. 8 (2008) 3137.; and Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, R. S. Ruoff, Adv. Mater. 22 (2010) 3906.—each incorporated herein by reference in its entirety]. The initial development of graphene from graphite was via acid treatment (Hummer's reaction) to exfoliate graphene sheets [W. S. Hummers, R. E. Offeman, J. Am. Chem. Soc. 80 (1958) 1339.—incorporated herein by reference in its entirety].
Making nanocomposites with unique functional properties from polyvinyl alcohol and graphene has attracted significant attention from researchers [Y. Xu, W. Hong, H. Bai, C. Li, and G. Shi, “Strong and ductile poly(vinyl alcohol)/graphene oxide composite films with a layered structure,” Carbon N. Y., vol. 47, no. 15, pp. 3538-3543, December 2009.; and J. Liang, Y. Huang, L. Zhang, Y. Wang, Y. Ma, T. Guo, and Y. Chen, “Molecular-Level Dispersion of Graphene into Poly(vinyl alcohol) and Effective Reinforcement of their Nanocomposites,” Adv. Funct. Mater., vol. 19, no. 14, pp. 2297-2302, July 2009.; and H. K. F. Cheng, N. G. Sahoo, Y. P. Tan, Y. Pan, H. Bao, L. Li, S. H. Chan, and J. Zhao, “Poly(vinyl alcohol) nanocomposites filled with poly(vinyl alcohol)-grafted graphene oxide,” ACS Appl. Mater. Interfaces, vol. 4, no. 5, pp. 2387-94, May 2012.; and X. Zhao, Q. Zhang, D. Chen, and P. Lu, “Enhanced Mechanical Properties of Graphene-Based Poly(vinyl alcohol) Composites,” Macromolecules, vol. 43, no. 5, pp. 2357-2363, March 2010.; and H.-D. Huang, P.-G. Ren, J. Chen, W.-Q. Zhang, X. Ji, and Z.-M. Li, “High barrier graphene oxide nanosheet/poly(vinyl alcohol) nanocomposite films,” J. Memb. Sci., vol. 409, no. 410, pp. 156-163, August 2012.; and C. Wang, Y. Li, G. Ding, X. Xie, and M. Jiang, “Preparation and characterization of graphene oxide/poly(vinyl alcohol) composite nanofibers via electrospinning,” J. Appl. Polym. Sci., vol. 127, no. 4, pp. 3026-3032, February 2013.; and Y.-S. Ye, M.-Y. Cheng, X.-L. Xie, J. Rick, Y.-J. Huang, F.-C. Chang, and B.-J. Hwang, “Alkali doped polyvinyl alcohol/graphene electrolyte for direct methanol alkaline fuel cells,” J. Power Sources, vol. 239, pp. 424-432, October 2013.; and H.-L. Ma, Y. Zhang, Q.-H. Hu, S. He, X. Li, M. Zhai, and Z.-Z. Yu, “Enhanced mechanical properties of poly(vinyl alcohol) nanocomposites with glucose-reduced graphene oxide,” Mater. Lett., vol. 102-103, pp. 15-18, July 2013. —each incorporated herein by reference in its entirety].
For example, Xu et al. reported the preparation of a PVA/graphene oxide nanocomposite that was shown to be strong and ductile in comparison to the pristine polymer. Liang et al. have also prepared PVA/graphene oxide nanocomposites by a simple solution mixing in water and casting method. The molecular level dispersion of graphene (only 0.7 wt. % of graphene oxide) in the polymer matrix significantly improved the mechanical strength properties in comparison to the native polymer.
Furthermore, Cheng et al. used PVA/graphene/graphene oxide instead of pristine graphene oxide alone to further improve the properties of PVA nanocomposites. The results showed a 88% increase in tensile strength, a 150% increase in Young's modulus and a 225% increase in elongation at break compared to the native polymer with only a 1% by weight loading of filler. Zhao et al. prepared a staple dispersion of graphene oxide in water with the aid of sodium dodecyl benzene sulfonate (SDBS) via sonication. The results demonstrated a 150% increase in tensile strength with the addition of 1.8% by weight graphene to the native polymer.
In addition, Huang et al. prepared PVA/graphene oxide nanosheet composites by a simple solution mixing process. A significant change was noted in the barrier property and the results lead to applications in the packaging industry. Wang et al. reported the characterization and preparation of PVA/graphene oxide nanocomposites via electrospinning methods. The results showed a decrease in decomposition temperature as well as a significant increase (42×) in tensile strength with a very low loading (0.02 wt. % of graphene oxide) in the PVA matrix.
Recently, Ye et al. demonstrated significant improvements in ionic conductivity and methanol crossover for a PVA membrane reinforced with graphene leading to fuel cell applications. Ma et al. prepared nanocomposite films of PVA and a glucose-reduced graphene oxide (rGO) by a solution blending method. The aqueous suspension stability of rGO was investigated by adding sodium dodecyl benzene sulfonate (SDBS) and poly(N-vinyl-2-pyrrolidone) (PVP). The results showed that PVP enhanced the dispersion of rGO in water significantly better than SDBS. Furthermore, the results showed an increased tensile strength and an increased Young's modulus for the nanocomposite films compared to the native PVA polymer.
In view of the forgoing, one aspect of the present disclosure is to design and provide nanocomposites with a non-uniform dispersion of carbon nanotubes in a polymeric matrix to introduce non-uniform electrical conductivity. It is envisioned that by this manner nanocomposites having the same or different local and bulk electrical resistivities can be produced. Another aspect of the present disclosure is nanocomposite films comprising a polymer layer, a conductive nanofiller layer, and a polysaccharide layer having antistatic properties at both the polymer layer and the polysaccharide layer. In addition, processes for forming the nanocomposites, methods for characterizing the nanocomposites as well as applications in or on electrical and/or electronic devices are provided.